The reduction in size of electronic devices and the improvement of their performance is accompanied by the reduction in size of the electronic components and structural parts and by an increase in their density. Electrical connectors are not an exception from this trend; there is a demand for electrical connectors with multiple contacts arranged in high density, for example, at a pitch of 0.5 mm. Such miniature high-density connectors are used as surface mount (SMT) components, and since, due to the small size of their terminals and narrow spacing separating them, they are not suitable for conventional methods of soldering; the so-called reflow soldering method is used for their mounting.
In recent years, due to the proliferation of such electronic appliances as video cameras, the demand has grown for miniature connectors for connecting PC boards and units. There is a particularly strong demand for surface mount connectors, which greatly facilitate electrical connections and make it possible to increase the density of electronic components. Such surface mount connectors usually include a receptacle-type connector soldered to a PC board and a plug-type connector soldered to another PC board which is to be connected to the former one. When these connectors are plugged together, their mating electrical contacts are electrically engaged thereby forming an electrical connection between the components of these PC boards. The connectors are usually equipped with locking devices located either on their outside or inside walls to prevent accidental disengagement.
However, using such locking devices either on the outside or inside of the connectors results in a more complicated structure and larger sizes, which prevents further increase in the mounting density on the boards. Therefore, attempts have been made to dispense with such devices, using instead the force of friction between the matching contacts of the plug-type and receptacle-type connectors in an engaged state (see patent Publication 88-285880).
These SMT connectors are known in the art. For example, the SMK Company of Japan markets the PB-10 connector with a 1 mm pitch for the connection of 2 parallel PC boards. However, since the contacts of this connector's plug are exposed, there is the danger of a short circuit if a conductive element comes into contact with the exposed contacts. This problem becomes even more acute if the pitch is reduced to 0.5 mm. In addition, it is impossible to provide a sufficiently large device locking the plug and receptacle in a connected position; as a result, the reliability of the connection deteriorates with repetitive plugging and unplugging of the connector. Besides, in the case of small-size electronic devices, the relatively small PC boards often must be connected not only parallel to each other, but also perpendicularly. Designing individual connectors for each specific application is far from economical.
Therefore, a new miniature surface mount connector is provided with high-density contacts (of the order of 0.5 mm) which can withstand frequent plugging and unplugging, and is suitable for connection of PC boards in a horizontal as well as a vertical position without substitution of at least one component.